Scooterotica

sean brady scooters wrote:http://books.google.co.uk/books?id=A9Ks ... ke&f=false

Its a good book had for years some good sound easy explained knowledge and is one of the best pages in the book.

It is all there as Tony is saying

House of Bamboo

can we not get all the book in pdf as i like reading stuff i dont understand

jonny snatchsniffer wrote:can we not get all the book in pdf as i like reading stuff i dont understand

Buy from Amazon £15 + post Bargain


Motorcycle Tuning Two-Stroke

sean brady scooters wrote:what ever the CC,torquey tunes still require massive port/time areas.........usually derived from widths formost .
area of ports rather than the duration of opening is the rule ...

So (bearing in mind I'm not that bright) what are the basic differences between ports on a super high BHP rev monster and those on something tuned for maximum torque for maximum rev range.

on the basis that im not so clued up i expect to be put right on this but i understand it (or not) as the width of the ports give torque whereas duration gives revs.

torqee tv200 exhaust port is like a letterbox... wide and shallow and a rev monster is likely to be round... tall as it is wide

thats basically it chaps...........

54.....
So given that most folk max out their port widths to within a mm of what the rings can handle surely the more CC's you add the more inefficient the top end becomes, despite it becoming more powerful?
Is this why Charlie E settled for 205 cc - a compromise over power / efficiency? Or did he just design such an improved exhaust system to overcome the lack of CC's?
I understand he comes from an automotive background but I have always been interested as to how a relative newcomer to scooters has achieved so much so quickly.

Had this conversation with Sean tonight....and whilst the Japs cottoned on to the volumetric efficiencies of 54x54, and multiplied their 125cc formula into twin 250s and v-four 500's......not every situation uses that formula (eg - your Lambo and Vespa doesnt come with that set-up, is probably not restricted to 125cc for any reason, and unless its a targa......its not a twin! ), and so different rules apply for different situations/requirements......

So, on a single cylinder scooter..... a 54x54 maybe say (for the sake of an example) 100% efficient, and a 72x64 thumper might be 80% efficient....tbut he thumpers 80% efficiency may still be more powerfull than the 54x54s 100%, and the 125 may be screaming to do, what the 260 does lower down the rev range and in more usable fashion.....but, port widths, degrees/durations, time-area, ring thickness, rod length, pipe, state of tune, final use of motor and all sorts of other s**t come into play......

But note, in the Robinson book quoted...all efficiency examples revolve around a 54x54 125cc example....so its easy to see when restricted to that 125cc capped example, how the 54x54 wins out....but it doesnt expalain in that chart what happens when you scale it up to and undersquare 58x54 or even 58x58 etc, etc when a 125 limit is not applicable.......

soullad wrote:....but I have always been interested as to how a relative newcomer to scooters has achieved so much so quickly.

Well, unless the man himself comes on here and answer the multitude of questions we would all want to throw at him...i guess we will never find out!

I did email Charlie an invite early on when we first got rolling, he replied to thank me for the invite, but explained that he was too busy with his work to get involved...and whilst that is a huge shame, it is perfectly understandable. And i cant see that anything would have changed in that area....in fact the better he does, the less likely he is to join and help us out!

So i dont think we will be getting any Q&A's with the champ any time soon!

soullad wrote:54.....
So given that most folk max out their port widths to within a mm of what the rings can handle surely the more CC's you add the more inefficient the top end becomes, despite it becoming more powerful?
Is this why Charlie E settled for 205 cc - a compromise over power / efficiency? Or did he just design such an improved exhaust system to overcome the lack of CC's?
I understand he comes from an automotive background but I have always been interested as to how a relative newcomer to scooters has achieved so much so quickly.

The 205cc is withing the group 4 rules so thats what he worked to. Charlie actually has been in business and has tuned race bikes (not necessarily just scooters) for around 14 years. Most of his stuff is road race /motocross yamahas, ktms etc. His approach is very different to any other tuner I've ever met and known. His work is about harmony, not buy this kit and that pipe with that carb. Everything works together,designed together.